In a large pot, melt 1 tablespoon of vegan butter over medium heat. Add chopped onion and sauté until translucent (about 5 minutes).
Stir in minced garlic and cook for an additional minute.
Cook the Mushrooms:
Add the sliced mushrooms (or vegetables) to the pot and sauté until they are tender and have released their moisture (about 5-7 minutes).
Add the Rice:
Stir in the Arborio rice, cooking for 1-2 minutes until the rice is lightly toasted.
Deglaze with Wine:
If using, pour in the dry white wine and cook until it is mostly absorbed by the rice.
Add Broth Gradually:
Begin adding warm vegetable broth, one ladle at a time, stirring frequently. Wait until most of the broth is absorbed before adding the next ladle. Continue this process for about 20-25 minutes, until the rice is creamy and al dente.
Finish with Vegan Butter and Milk:
Once the rice is cooked, stir in the remaining vegan butter and plant-based milk. Season with salt and pepper to taste.
Serve:
Serve hot, garnished with fresh parsley if desired.